Acoustical apparatus



Dec. 10, 1940. c. R. JACOBS ACOUSTICAL APPARATUS Filed Nov. 9, 1959 3Sheets-Sheet l JONFZOU Dec. 10, 1940. c. R. JACOBS ACOUSTICAL APPARATUSFiled Nov. 9, 1939 3 Sheets-Sheet 2 Dec. 10, 1940.

c. R. JACOBS 2,224,651

ACOUSTICAL APPARATUS Filed Nov. 9, 1939 5 Sheets-Sheet 3 OUTER.

WALL

Patented Dec. 10, 1940 UNITED STATES PATENT OFFICE 12 Claims.

This invention relates to sound control or acoustical apparatus for useprimarily in radio broadcasting studios, recording studios, theaters andanalogous sound chambers.

An object of the invention is to provide acoustical apparatus forinstallation in a studio or other sound compartment capable of selectiveamplification or reinforcement and reflection of tones and selectivevariation of acoustical con- 1 ditions within the studio.

Another object of the invention is to provide acoustical apparatusembodying control elements having resonating qualities at givenfrequencies I which bring out the natural, true tones of the 1instruments from which the sound emanates, said elements beingadjustable or movable to change their natural frequencies and also varythe reverberation time of the studio or other enclosure.

Another object is to provide a highly efiicient sound control apparatuswhich is capable of silent operation and which is relatively simple inconstruction and installation.

More specifically, the invention contemplates 23 sound control elementsin the form of adjustable acoustical vanes or panels preferably ofpredetermined vibratory characteristics having predetermined resonatingcharacteristics at given frequencies and arranged in cooperativerelation '30 with a sound absorbing surface, the vanes or panels whenadjusted varying the degree of exposure of said surface to thereby varythe reverberation time of the studio. These vanes when in closed orsubstantially closed position provide 36 a serrated or Vd wall creatinga diffused sound condition within the studio or other enclosure. Thepanels or vanes preferably have absorption factors and characteristicsof predetermined relative values, viz, they absorb a certain percentageof sound at a given frequency or cycle and reflect or in effect add acertain percentage of sound at another frequency or cycle, there being adefinite relationship between the cycles of absorption and reflectionwhich tend to bring out or emphasize tones which would otherwise beobscured in a broadcast while at thesame time modulating other tones andmerging the whole in proper harmony.

The various objects and advantages of the invention will become moreapparent in view of the following description taken in conjunction withthe drawings, wherein:

Fig. 1 is a schematic plan view of a radio broadcasting studioconstructed in accordance with the features of the present invention;

Fig. 2 is an enlarged detail view in top plan and partly in section of anumber of the panels or vanes of Fig. 1 and the sound absorbing surfaceor wall in rear thereof;

Fig. 3 is a view similar to Fig. 2 with the exception that itillustrates a difierent or alternate type of vane;

Figs. 4 and 5 are views in sectional elevation taken transversely ofFigs. 2 and 3, respectively, Fig. 4 illustrating the operating mechanismfor the vanes of Fig. 2 and Fig. 5 the operating mechanism for the vanesof Fig. 3.

Referring to the drawings in detail, in Fig. 1 I have shown a proposedplan for a radio broadcasting studio. For the purposes of illustrationthe studio is divided into three compartments 5, 6, and l. The walls 8and 8a of the compartment 5 may be provided with a sound-absorbingsurface such as fabric, cork or other suitable material or may becomprised wholly or partly of 20 sound-absorbing or deadening material.In front of these acoustical walls are mounted a plurality of vanes orpanels, each of which is generally indicated at 9 and the preferred formof which is shown in detail in Fig. 2. These vanes or 25 panels are atleast in part constructed to have certain desirable resonatingcharacteristics. Their function may be compared with that of the soundbox or body of a violin. They may be constructed and arranged to absorb11% of the 30 sound at cycles, reflect or, in effect, amplify or add 25%of the sound at cycles; absorb 22% of the sound at cycles; reflect oradd 6% at 200 cycles; absorb 28% at 500 cycles; amplify 8% at 1000cycles; absorb 13% at 1500 cyles, 7% at 2000 cycles and 3% at 4000cycles. There is thus a definite relationship in the resonance of thepanels at 100, 200, 1000, 2000 cycles which result in the emphasizing ofcertain tones and the modulating of others as will be more 4 fullyhereinafter described. The term amplify as used herein means that thetone is intensified or enriched by supplementary vibration.

The material of which the panels are made may of course vary. Inpractice, ply wood has -45 proved satisfactory. One side or shell of thepanel, for example the inner shell 9a, may be 7- ply with a totalthickness of one-half inch. While, of course, the thickness or ply mayvary, it is desirable that one side of the panel be as 50 rigid andresonate as possible. The wood used should be of the hard dense variety.The other shell or outer side 9b of the panel may be made up of 5-plywood with a total thickness of onefourth inch. The wood for this side ofthe panel 55 is preferably soft and porous. Airplane spruce I has beenfound satisfactory.

The height of the panels may, of course, vary. Those illustrated hereinare 14' high or long. They have a center thickness of 4 graduallytapering as they recede from their pivot point to a relatively bluntedge, with an overall blade and other factors influence their frequencycharacteristics, and hence these factors are subject to variation inaccordance with conditions desired for a given studio or enclosure. Eachvane is also preferably provided with a sounding post 90, and theposition of the post also affects the frequency characteristics. Thissounding post may consist of a dowel pin made up of a round piece ofwood ofsay, for example, /2" in diameter, and is shown locatedapproximately centrally of each panel.

By observing Fig-g2, it will be noted that the pivot points or axes ofthese vanes are spaced with respect to one another so that when theiredges are brought into contact a wall having a serrated orundulatingsound-diffusing contour is provided, such wall being indicatedat 9 in Fig. 1. Thus, the spacing between the axes or pivot points ofthe respective vanes may be approximately 2'3", resulting, when thevanes are closed, in a serration having an approximate maximum depth of6".

The vanes are pivotally mounted and may be arranged sothat they areselectively adjustable or rotatable in groups; that is, a certain groupof panels covering a certain all area which may be independently,adjustable with respect to another group. Any suitable means may beprovided for adjusting or operating the panels.

7 Fig. 4 in conjunction with Fig. 2 illustrates a type of operatingmechanism which may be used for operating the panels or vanes 9. Eachpanel is provided with end shafts or axes II and Ila, which are mountedfor rotation in bearing brackets in the 1" orm of angle members Ill) andHe. The lower spindle or shaft Ila projects through the floor or baseboard and is provided with a sprocket [2 having a sprocket chain I3 inmesh therewith, the chain being trained over alternate sprockets asindicated in Fig. 2, so that one panel or base is turned clockwise andits adjacent panel counterclockwise. The sprocket chain l3 may be drivenfrom a suitable electric motor M operating through a reduction unit. Thecontrols for the motor, not shown, may be arrangd for operation from acentral point, for example, from the control room indicated in Fig. 1,and which may be the desk of a monitoring engineer, a producers desk ora sound effects engineers control panel. The operating mechanism isshown housed in awall compartment l4 accessible by means of a removablepanel Ma.

In Fig. 3 an alternate form or type of panel is illustrated which may beused instead of, or in conjunction with the panels 9. These panels orvanes are each generally indicated at I5 and instead of being mounted ona central or center axis and gradually tapering toward opposite edges,they are mounted on vertical shafts or axes l6 and 160; located adjacentone edge thereof, or the thicker edge. As far as the actual constructionof the panelsis concerned, the shells or opposed Walls thereof .may besubstantially similar to the walls of the panels 9, the inner shell 15a,being rigid and resonate and therefore formed of relatively hard densewood, for example '7-ply; and the opposite shell I51) of the panel beingmade of relatively soft and porous wood of 5-ply. The panels l5 at theirthickest point may be approximately 3 /2 tapering to a relatively bluntedge having a bumper or guard l6 thereon; and the overall Width of theblade of each vane may be approximately .39", with a spacing betweenpivot points of approximately 36" so that when the vanes are closed theywill slightly overlap, providing a resonating or soundreflecting Wallhaving a substantially flat sur face contour. With this type of vane,the serrated or undulating diffusion wall is less pronounced than withblades of the type used for the wall 9. Thus, part of the studio may beequipped with vanes which provide a serrated or difiusion wall of thetype indicated at 9' while other portions of the studio may be providedwith vanes which when closed result in a wall such as that indicated at15.

In rear of the. vanes 15 are sound-absorbing acoustical walls 8b, suchas the walls 8, 8a used in the rear of the vanes 9 of the compartment 5.

The type of operating mechanism illustrated for the. vanes Iii is variedwith respect to that used for the vanes 9, note Fig. 3 in connectionwith Fig. 5. The bottom pivot or shaft lGa for each of the vanes I5 isprovided with a sprocket I! having a sprocket chain l8 trainedthereover. Any selected one of the shafts Ilia may be provided with adrive connection, illustrated in the form of an arm l9, having pivotallyconnected thereto a link 20 which in turn connects with an arm 2|secured on a shaft 22 driven by a motor M. In this instance, the driveis of the oscillating type, and hence the motor 23 may be of thereversing type. 7

As in the case of the drive mechanism for the vanes 8, the various driveunitsmay be located in a compartment immediately above the floor level,the controls for the motor 23 being operable from a central point.

The center compartment 6 may have a conventional wall structure and isso illustrated, although it will be obvious that any portionor all ofthe walls of this compartment could also be provided with adjustableacoustical vanes 9 or l5 having a sound absorbing wall in rearthereof.

The walls of the studio are preferably constructed in a manner such thatopposite surfaces are non-parallel, thereby avoiding concentration ofsound at any one spot and preventing either dead spots or flutters. -Theletters S. L. in Fig; l

of the drawings are an abbreviation for the words sound look, a termused to designate a vestibule between the studio and a public spacewhich is given acoustical treatment to prevent leakage of sound. Thespace or compartment marked control indicates the room wherethe controldesk, panels orlike parts are located.

As far as the operation of the apparatus is concerned, it will beobvious that such may vary inaccordance with the acoustical resultsdesired. For example, let it be assumed that a program is to bebroadcast simulating a choral group advancing along a street and into acathedral. When the choral group starts singing, the panels would beopen, providing maximum exposure of the acoustical walls 8, 8a, 8b tothe soundwaves and creating the deadest possible condition in thestudio. The panels would be gradually adjusted 16 toward closedposition, and'when the program reaches the point where the choral groupis supposed to be moving over the threshold of the cathedral, the panelswould be completely or almost completely closed, thereby giving maximumsound resonanceand reflection and creating a sense of proximity of thesingers to the radio audience, due to the fact that the studio has beenchanged from say, for example, .5 seconds reverberation time (a deadstudio) to say 1.2 seconds reverberation time (a very live studio forthe volume concerned in this particular instance).

When the panels are in their normal or closed position, the lessresonant side (81) or l5b) is preferably exposed to the sound chamber.However, the panels may be readily operated to expose the more resonantside (9a or I50.) during a program, the full or wide range andflexibility of adjustment being one of the features of the presentinvention.

The natural frequencies of the vanes or panels will change when they aremoved out of edge-toedge contact with one another. Thus, the naturalresonance or vibratory characteristics of each panel is increased as itmoves out of contact with its adjacent panel, the panels havingdifferent absorption characteristics when open than when in contact. Theresult is that the reverberation times at the various frequencies changewhen the panels are opened and closed, the extent of the changedepending upon the number of panels moved and the volume of the room, aswell as the type of absorbing treatment of material in rear of thepanels.

Another important feature of advantage is that a studio constructed asdisclosed herein may be used for an entire program which wouldordinarily require a plurality of studios. For example, where a programwhich heretofore re.- quired a studio for the cast, an adjoining studioor compartment for musical accompaniment, and a still further area orcompartment for sound effects, the entire program could be put on in thepresent studio by creating a relatively live or reverberate condition inone end of the studio and a relatively dead or non-reverberate conditionin the other end thereof.

A further feature of advantage is that the acoustical vanes disclosed inthe present invention may be utilized to bring out tones of a frequencywhich would otherwise be obscure. For example, with studios asheretofore constructed, considerable difficulty has been experienced inbringing out tones having certain frequencies, a first violin beingtypical. An orchestral program in which there were around twelve firstviolins ofttimes sounded as though there were say, for example, onlyfour first violins. The construction of the panels 9 and I5 is such asto bring out tone frequencies such as those emanating from a. firstviolin in their natural state, while at the same time modulatingfrequencies in lower or higher ranges. Thus, assuming that during a testthe sound or tone of a given frequency in a given studio was firstmeasured and indicated 100 units with a decay period of 1.00 seconds,and panels of the type disclosed herein having a similar resonancefrequency were then placed in the studio, the decay period would beapproximately 1.25; whereas if the sound had a frequency below or abovea frequency of 100 cycles, this reflecting action would be lessened andequalized. Thus the tones of the first violins would be rendered naturaland distinct while at the same time tones equipped with my improvedacoustical apparatus.

No attempt has been made herein to list all the advantages of theimproved acoustical apparatus, nor have the various methods ofinstalling and utilizing the same been stated in detail. For ex ample,it may be desired to install the vanes on the side walls and ceiling,and even on the floor, or adjacent the latter. Ordinarily, only acertain portion of the walls of the studio need be equipped with theimproved acoustical vanes and soundabsorbing or deadening wall in rearthereof and the remaining walls constructed to obviate undue resonanceand reverberation.

It will be obvious that the foregoing and other changes in constructionand design may be adopted without departing from the spirit or scope ofthe invention as defined by the appended claims.

What is claimed is:

1. Acoustical apparatus including a. plurality of acoustical vanes foruse in an acoustic chamber, each of said vanes consisting of a hollowelongated body having opposed panels joined at their longitudinal edgesand convexly outwardly curved with respect to a longitudinal axis ofsaid vane, one

of said panels being formed of rigid, thin, dense sound-refiecting,resonant material and the other of said panels being formed ofrelatively soft sound-absorbent material.

2. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamber,

each of said vanes consisting of a hollow elongated body having opposedpanels at least one of which is convexly outwardly curved with respectto a longitudinal axis of said vane, one of said. panels being formed ofrigid, dense sound-reflecting,

resonant material and the other of said panels being formed ofrelatively soft, less rigid and less resonant material, said panelsbeing joined at their longitudinal edges.

3. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamber, said vanes each including a pair of concavepanels arranged in opposed relation to provide a hollow elongated body,one of said panels being of rigid, thin, dense material to impartresonating and sound-reflecting properties to the vane and the other ofsaid panels being of relatively soft material capable of absorbingsound.

4. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamber, said vanes each comprising a pair of concavepanels arranged in opposed edge-to-edge relation to provide a hollowelongated body, one of said of rigid, thin, dense material to impartresonating and sound-reflecting properties to the vane and the other ofsaid panels being of relatively soft material capable of absorbingsound, means pivotally mounting said vanes whereby they may be adjustedto varying degrees of exposure to sound Waves, the pivotal spacing ofsaid vanes being such that when they are adjusted to closed positiontheir edges are brought into contact providing a surface of serrated orundulating sound diffusing contour.

6. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamber, said vanes each including a pair of concavepanels arranged in opposed relation and joined at their longitudinaledges to provide a hollow elongated body, one of said panels being ofrigid, thin, dense material to impart sound-resonating andsound-reflecting properties to the vane and the other of said panelsbeing formed of relatively soft material capable of absorbing sound,means pivotally mounting said vanes whereby they may be adjusted tovarying degrees of eX- posure to sound waves, the pivotal axes of saidvanes being spaced apart a distance less than the Width of the vane sothat when the vanes are adjusted to closed position their edges contactone another varying the natural resonance or vibratory characteristicsof the vanes, said vanes having the edges thereof provided with aresilient bumper to ensure quiet operation.

7. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamber, said vanes each comprising a pair of concavepanels arranged in opposed relation and joined along their longitudinaledges to provide a hollow elongated body, one of said panels being ofrigid, dense, sound-reflecting and resonant material and the other ofsaid panels being of relatively soft, less rigid and less resonantmaterial, means pivotally mounting said vanes, and a sound-absorbingsurface in the rear of said vanes.

8. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamber, each of said vanes consisting of a hollowelongated body having opposed panels joined at their longitudinal edgesand oonvexly outwardly curved with respect to a longitudinal axis ofsaid va one of said pa e s e ng o igi nse;

sound reflecting and resonant material and the curved contour, saidwalls being in part formed of hard, rigid, resonant material and in partof less rigid and less resonant material capable of absorbing sound, andmeans rotatably mounting said vanes.

10. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamber, said vanes each comprising an elongatedhollow body having opposed convexly curved vibratory walls, one of saidwalls being of hard, rigid, resonant material and the other of saidwalls being of less rigid and less resonant material, and meansrotatably mounting said vanes.

11, Acoustical apparatus including a plurality f a s ca vanes ior s inan ac us chamber, said vanes each comprising a hollow elongated bodywith walls shaped to provide a sound box of elliptical shape in crosssection, said walls being of varying degrees of rigidity and hardness tothereby vary the sound-reflecting and soundabsorbing qualities of thevane While at the same time imparting resonance tothe vane as a whole,and means rotatably mounting said vanes forvarying degrees of exposureto sound vanes.

12. Acoustical apparatus including a plurality of acoustical vanes foruse in an acoustic chamher, said vanes each comprising a hollowelongated body functioning in the nature of a sound box and having wallsof varying degrees of ri gidity and hardness circumferentially of thebody to thereby vary the sound-reflecting and sound-absorbing qualitiesof the vane while at the same time imparting resonance to the vane as awholeyand means rotatably mounting said vanes for varying de rees ofexposure to sound waves.

CLARENCE R. JACOBS.

